Power tool guard

ABSTRACT

A power tool including a power tool body, a rotatable driven member being operable for releasably gripping a working element and having a front end and a rear end, the driven member extending from the rear end, located proximally and connected to the power tool body, and terminating at the front end. The power tool has a drive mode in which rotation of the driven member drives the working element relative to the power tool body and an adjustment mode in which rotation of the driven member causes the driven member to either grip the working element or release the working element or both. The power tool also includes a guard extending over the driven member from the power tool body and terminating adjacent to the front end of the driven member, wherein at least in the power tool drive mode the front end of driven member does not extend beyond the guard. In another aspect the guard has a surface for gripping the power tool between the front end of the driven member and the power tool body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a U.S. National Phase Patent Application based on InternationalPatent Application Serial No. PCT/AU2007/000371 filed on Mar. 23, 2007,the disclosure of which is expressly incorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to power tools of the type incorporating a drivenmember adapted to releasably grip at least one working element. Theinvention is applicable to tools in which the working element is a drillbit, a saw blade, a cutting wheel, a grinding wheel, or any otherelement used to cut, shape, or otherwise treat a work piece, or is adriving element such as a screwdriver blade, or a socket spanner.

A power drill is one form of power tool to which the invention isapplicable. For the sake of convenience the invention is described belowin the context of power drills, but it is to be understood that theinvention has broader application.

BACKGROUND OF THE INVENTION

Existing power drills usually have a three jaw chuck for gripping adrill bit. The chuck jaws are adjustable to suit drill bits of varioussizes. In most cases such adjustment is carried out by use of a key orby manually twisting the outer sleeve of the chuck or alternatively theuser grips the outer sleeve and power is applied to the chuck, wherebythe user provides a resistance force.

In such arrangements, however, when the chuck jaws are gripping anddriving a drill bit into a work piece the jaws may come into contactwith the work piece and damage it. In addition, the chuck, including thechuck jaws, may be exposed to damage and the ingress of dust into movingparts within the chuck.

Further drawbacks associated with the above arrangements include thatthe closest a user can grip the drill body is behind the rearmost partof the chuck some distance away from the drill bit and the work piece.Furthermore, it is possible that a user may, when using the drill, gethair, clothing or body parts caught in the chuck or the chuck jaws.

Existing drill arrangements have incorporated a light source forproviding light in the work area. Such arrangements include a lightsource located on the main body of the drill and rearward of the chuck.Thus, the light source is located a distance from a work surface thatresults in a relatively low intensity light on the work surface andrequires adjusting the focus point of the light in the area in whichwork is to be carried out. Also, if the chuck is located between thelight and the work surface then when the light is in use the chuck cancast a shadow on the work surface.

SUMMARY OF THE INVENTION

The present invention ameliorates the problems set out above withrespect to existing power tool arrangements by providing, in a firstaspect, a power tool including:

a power tool body;

a rotatable driven member being operable for releasably gripping aworking element and having a front end and a rear end, the driven memberextending from the rear end, located proximally and connected to thepower tool body, and terminating at the front end;

the power tool having a drive mode in which rotation of the drivenmember drives the working element relative to the power tool body and anadjustment mode in which rotation of the driven member causes the drivenmember to either grip the working element or release the working elementor both;

a guard extending over the driven member from the power tool body andterminating adjacent to the front end of the driven member, wherein atleast in the power tool drive mode the front end of driven member doesnot extend beyond the guard.

This aspect of the present invention is advantageous in that it providesa power tool, an example of which is a power drill, that has a drivenmember, which in the case of a power drill may be a chuck, that isoperable for gripping and releasing a working element by rotation of thedriven member, which in the case of a power drill means activating amotor that drives rotation of the chuck, when the driven member is inthe adjustment mode. This aspect of the invention also provides, incombination with the above, a guard that can protect the driven memberand can protect a user from the driven member when it rotates. The guardcan also provide an additional gripping surface forward of the body ofthe power tool and adjacent the driven member.

Preferably, the guard has a surface for gripping the power tool betweenthe front end of the driven member and the power tool body. Morepreferably, the gripping surface is at least partially formed out of aresilient material. In one form, a majority of the gripping surface isformed out of a resilient material, whereas, in another form, a minorityof the gripping surface is formed out of a resilient material. Theseforms of the invention are advantageous in that they enable a user tohold the power tool much closer to the working element than haspreviously been possible with existing power tools employing a drivenmember for releasably gripping at least one working element and having aworking mode for driving movement of the working element relative to thepower tool body. They may also assist in providing a more sure gripand/or damping of vibration transmitted to the user's hand.

In a preferred form, the invention may include a resilient membermounted to the guard adjacent the front end of the driven member,wherein at least in the power tool drive mode the front end of drivenmember does not extend beyond the resilient member for preventing theguard from leaving an impression on a work piece. In another form, theresilient member may be mounted to the guard adjacent and forward of thefront end of the driven member. These forms of the invention may preventthe driven member from directly contacting a work-piece for the workingelement, however, they may also prevent the guard from leaving animpression on the work piece and leaving an unsightly mark. Theseembodiments are particularly beneficial where, for example, thework-piece is a piece of relatively soft material such as soft-wood andwhere the use of existing power tool arrangements pose a risk that thedriven member will come into contact with the soft material and abradeor leave a divot in the soft material.

In one form, the guard is rotatable relative to the body of the powertool for adjusting the amount of torque supplied to the driven member.Preferably, the amount of torque supplied to the driven member isadjusted by a torque controller that is actuable to different torquesettings by the rotation of the guard. In another preferred form, thetorque controller is a mechanical torque controller.

In another form, the guard includes a graduated indicator for differentamounts of torque. Alternatively, the body includes a graduatedindicator for different amounts of torque.

In another form the guard is substantially axially aligned with an axisof the driven member that drives movement of the working element bysubstantially moving relative to the axis. Preferably, the guard issubstantially cylindrical and tapers from a larger diameter at the powertool body and to a smaller diameter adjacent the front end of the drivenmember. In these forms of the invention, the user may grip the powertool by holding the guard any position about the periphery of theworking element.

Preferably, the guard is integral with the power tool. In another formthe guard is detachable from the power tool body to reveal the drivenmember.

In another form, the power tool of the invention may further include alight source mounted to the guard adjacent the front end of the drivenmember. In another form, the light source is detachable from the guard.The light source may be used to provide light on a work area for theworking element. This arrangement is advantageous over existing powertools that incorporate a light source or have a light source attached,whereby the position or orientation of the light source must be adjustedto focus the light in the area where work is to be carried out by theworking element. By providing a light source adjacent the front end ofthe driven member, which is the closest part of the power tool to thework area, this embodiment of the invention obviates the need to adjustthe position or orientation of the light source to focus on the workarea.

In another form, the power tool of the invention further includes abearing mounted between the guard and the driven member forward of therear end of the driven member. The bearing may be any type of bearingsuch as a ball bearing type bearing. Alternatively, the power tool ofthe invention may include a bush or a contact surface between the guardand the driven member. The advantage of these arrangements is that thedriven member is supported forward of the rear end of the driven memberwhereas in existing arrangements, the driven member is only supportedbehind the rear end of the driven member, some distance away from theworking element which is subject to forces in various directions arisingfrom contact with, and work being conducted, on the work-piece.

In a particularly preferred form of the invention, the power tool is apower drill and the driven member is a chuck with gripping jaws adaptedto grip the working element in the form of a drill bit.

In another aspect, the present invention provides a power toolincluding:

a power tool body;

a rotatable driven member being operable for releasably gripping aworking element and having a front end and a rear end, the driven memberextending from the rear end, located proximally and connected to thepower tool body, and terminating at the front end;

the power tool having a drive mode in which rotation of the drivenmember drives the working element relative to the power tool body and anadjustment mode in which the driven member either grips the workingelement or releases the working element or both;

a guard extending over the driven member from the power tool body,terminating adjacent the front end of the driven member and having asurface for gripping the power tool between the front end of the drivenmember and the power tool body, wherein at least in the power tool drivemode the front end of driven member does not extend beyond the guard.

In a preferred form, the gripping surface is at least partially formedout of a resilient material, preferably a resilient polymer. In anotherform the gripping surface is shaped to provide additional grip.

BRIEF DESCRIPTION OF THE FIGURES

The present invention will now be described in more detail withreference to the following Figures. The following Figures representembodiments of the invention in the form of a hand held power drill andfor the sake of convenience the present invention is described below indetail with reference to the power drill embodiment. It is to beappreciated, however, that the present invention may be suitable for usewith various other forms of power tool such as, without limitation, handheld power saws, power screw-drivers, power percussion/hammer drills andany other power tool that utilises a driven member that releasably gripsand drives movement of a working element relative to the power toolbody.

FIG. 1 illustrates in diagrammatic form a hand held power drill inaccordance with a preferred embodiment of the invention that includes apower tool body and a mechanical driven member that is obscured by aguard extending from the front of the power tool body.

FIG. 2 is a schematic illustration of the power drill of FIG. 1illustrating some internal features of the power drill including themechanical driven member connected to the power tool body that isoperable for releasably gripping and driving a working element.

FIG. 3 is a schematic illustration of the embodiment of the power drillof FIG. 2 further including a bearing mounted between the guard and thedriven member.

FIG. 4 is a schematic illustration of the embodiment of the power drillof FIG. 3 further including a light source mounted to the guard.

FIG. 5 illustrates in diagrammatic form a hand held power drill inaccordance with a preferred embodiment of the invention that includes apower tool body and an electronic driven member that is obscured by aguard extending from the front of the power tool body.

FIG. 6 is a schematic illustration of the power drill of FIG. 5illustrating some internal features of the power drill including theelectronic driven member connected to the power tool body that isoperable for releasably gripping and driving a working element.

FIG. 7 is a schematic illustration of the embodiment of the power drillof FIG. 6 further including a bearing mounted between the guard and thedriven member and a light source mounted to the guard.

FIG. 8 is a schematic illustration of the power drill of FIG. 1including a working element in the form of a drill bit boring through awork-piece illustrating the way in which the guard prevents the drivenmember from contacting the work-piece when the power drill is in thedrive mode.

DETAILED DESCRIPTION

FIGS. 1 to 8 illustrate a preferred embodiment of the invention in theform of a hand held power drill 10, however, the invention is applicableto other power tools that may or may not be hand held or portable. Thepower drill 10 includes a power drill body 20 integrally formed with apistol grip handle 60 for gripping the power drill 10. While thearrangement of the handle 60 illustrated in the drawings is in the formof a pistol grip that is moulded to the shape of a user's hand, that is,the grip includes depressions to receive the fingers of a user, it is tobe appreciated that other shapes and configurations of handle 60 may beemployed. The body 20 of the power drill 10 has a generally cylindricalshape and encases components of the power drill 10 such as a motor 30.Incorporated into the handle 60 adjacent to the body 20 of the powerdrill 10 are a switch 50 and a trigger 55 for actuating the switch 50.Also incorporated into the handle 60 but distally from the body 20 ofthe power drill 10 is a battery 40 and a battery retaining and releasingmeans 45 that enables convenient replacement of the battery 40 asrequired. In another form, not illustrated, the power drill 10 mayexclude the use of the battery 40 and may instead have a power leadextending from the handle 60, or any other suitable location, thatconnects to a mains power outlet to supply power to the power drill 10.

The power drill 10 also includes a driven member 70 having an axis ofrotation. A rear end 75 of the driven member 70 is connected to themotor 30. The driven member 70 extends from the rear end 75 andterminates at a front end 80 of the driven member 70. Operation of themotor 30 causes the driven member 70 to rotate in either forward orreverse directions.

In the particular arrangement shown, the driven member 70 is a three jawchuck arrangement that includes a head portion 76 at the front end 80having a plurality of jaws 85, 86 mounted to the head portion 76 in anangular orientation relative to the axis of the driven member 70. Eachjaw 85, 86 has a gripping face 87, 88 adapted to clamp against the shankof a working element such as a drill or screwdriver bit 155. Adjustmentmeans are provided to enable the jaws 85, 86 to move as required toadjust to the diameter of the shank of the bit 155 to be gripped.

Each jaw 85, 86 is slidably mounted to the head portion 76 of the drivenmember 70 so as to be movable relative to the head portion 76 on a paththat is angularly displaced relative to the axis of the driven member70. The adjusting means includes an adjusting nut 72 that meshes witheach jaw 85, 86 through a thread or worm connection. The arrangement ofthe adjusting means is such that rotation of the driven member 70including the head portion 76 of the driven member 70 and the jaws 85,86, caused by operation of the motor 30, relative to the adjusting nut72 causes the gripping face 87, 88 of each jaw 85, 86 to move towards oraway from the axis of the driven member 70 while simultaneouslyprojecting each jaw 85, 86 outwardly or retracting each jaw 85, 86inwardly relative to the head portion 76 of the driven member 70.

When a drill or screwdriver bit 155 is to be inserted between the jaws85, 86 for gripping by the gripping face 87, 88 of each jaw 85, 86, thedriven member 70 is adjusted by operating the motor in one direction ofrotation so that the head portion 76 and the jaws 85, 86 rotate relativeto the adjustment nut 72 such that each jaw 85, 86 moves away from theaxis of the driven member 70 and retracts inwardly relative to the headportion 76 of the driven member 70. The shank of the bit 155 is insertedbetween the jaws 85, 86. The driven member 70 is adjusted again byoperating the motor in the reverse direction of rotating so that thehead portion 76 and the jaws 85, 86 also rotate in the reverse directionrelative to the adjustment nut 72 and each jaw 85, 86 moves towards theaxis of the driven member 70 and projects outwardly relative to the headportion 76 of the driven member 70 to clamp the bit 155 between thegripping face 87, 88 of each jaw 85, 86.

As is shown in FIGS. 1 to 8 a guard 90 extends from the power drill body20 adjacent the rear end 75 of the driven member 70. The guard 90extends from the power drill body 20 over the driven member 70 andterminates at a front end 95 of the guard 90 adjacent the front end 80of the driven member 70. The guard 90 may be integral with the body 20of the power drill 10 and is substantially cylindrical and tapers from alarger diameter at the body 20 of the power drill 10 to a smallerdiameter opening at the front end 95 of the guard 90 adjacent the frontend 80 of the driven member 70. The guard 90 is also substantiallyaxially aligned with the axis of rotation of the driven member 70.Although the guard 90 illustrated in the drawings is substantiallycylindrical and tapers from a large diameter to a smaller diameteropening, such that it has a conical shape, it is to be appreciated thatthe guard 90 may have other shapes and be equally suitable for itspurpose. For example, the guard 90 may have a substantially cube orrectangular prism shape. In this form, the guard 90 would include fourinterconnected sides extending from the body 20 of the power drill 10that may taper, or not taper, to a square shaped opening at the frontend 95 of the guard 90. In these forms, the guard 90 would have asubstantially square cross section. Other forms of the guard 90 couldinclude a hexagonal or octagonal cross section or any other form ofcross section and may include tapering or no tapering and may includesides that are interconnected at sharp edges or rounded edges.Alternatively, the guard 90 may be shaped to conform to a user's hand.In this form, the guard 90 may include depressions for receiving thefingers of a user to provide enhanced comfort and grip.

The guard 90 illustrated in FIGS. 1 to 8 can be gripped by a user androtated about an axis of the guard 90 relative to the body 20 of thepower drill 10. As is particularly shown in FIGS. 2, 3 and 4, the guard90 is coupled to a torque control means 185 for controlling the amountof torque transmitted from the motor 30 to the driven member 70. Whenthe guard 90 is rotated in one direction it adjusts the torque controlmeans 185 to reduce the maximum amount of torque that the motor canimpart to the driven member 70. On the other hand, when the guard 70 isrotated in the reverse direction it adjusts the torque control means 185to increase the maximum amount of torque transmitted from the motor 30to the driven member 70. The guard incorporates a graduated indicatorfor when different torque settings for the torque control means 185 havebeen selected. Alternatively, the body 20 may include a graduatedindicator for when different torque settings for the torque controlmeans 185 have been selected.

In another form, as illustrated in FIG. 5 in particular, the guard 90may not be integral with the body 20 of the power drill 10 along a joint92 to reveal and enable access to the driven member 70 and its three jawchuck arrangement including the head portion 76, the plurality of jaws85, 86, the rear end 75 of the driven member coupled to the motor 30 andany other component of the power drill 10 located between the motor 30and the front end 80 of the driven member 70. The means of connection ofthe guard 90 and body 20 may take any suitable form including, forexample, a twist and lock arrangement or a snap lock arrangement.

As is shown in FIGS. 2, 3, 4, 6, 7 and 8 the guard 90 is shownterminating adjacent and level with each jaw 85, 86 when the grippingfaces 87, 88 of the jaws 85, 86 are in contact with each other and thejaws 85, 86 are in their forward most position relative to the headportion 76 of the driven member 70 and relative to the guard 90. Inorder for a bit 155 to be placed between the gripping faces 87, 88 thedriven member 70 must be adjusted by rotating the head portion 76 of thedriven member 70 relative to the adjustment nut 72 such that each jaw85, 86 moves angularly away from the axis of the driven member 70 andretracts inwardly relative to the head portion 76 of the driven member70 to provide a space between the gripping faces 87, 88 for receivingthe bit. Accordingly, when the driven member 70 has been so adjustedeach jaw 85, 86, which form the front end 80 of the driven member 70, isrearward of the front end 95 of the guard 90 such that the front end 80of the driven member 70 will be located substantially inside the guard90.

When the driven member 70 is subsequently further adjusted by rotatingthe head portion 76 in the opposite direction relative to the adjustmentnut 72 such that each jaw 85, 86 moves angularly toward the axis of thedriven member 70 and projects outwardly relative to the head portion 76to close the space between the gripping faces 87, 88 for clamping thebit between the jaws 85, 86, the jaws 85, 86, which form the front end80 of the driven member 70, remain rearward of the front end 95 of theguard 90 such that the front end 80 of the driven member 70 will remainlocated substantially inside the guard 90.

When the power drill 10 is in use, a drill or screwdriver bit 155gripped between the jaws 86 of the driven member 70 and initially isplaced in contact with a work piece 160. A forefinger of a user's handgripping the handle 60 then activates the power drill 10 by depressing atrigger 55 on the handle 60. Depressing the trigger 55 actuates theswitch 50 inside the handle 60 that enables current to flow from thebattery 40 to the motor 30. The motor 30, which is connected to the rearend 75 of the driven member 70, subsequently drives rotation of thedriven member 70 to, in turn, drive rotating movement of the drill orscrewdriver bit 155 for boring or driving a screw into the work-piece160 of timber, masonry or the like. Thus, the power drill 10 has a drivemode in which current flowing from the battery 40 to the motor 30 drivesrotating movement of the driven member 70 that, in turn, drives rotatingmovement of the drill or screwdriver bit 155 relative to the body 20 ofthe power drill 10.

Accordingly, when the power drill 10 is in the drive mode in which thedriven member 70 drives movement of the drill or screwdriver bit 155relative to the body 20 of the power drill 10 the front end 80 of thedriven member 70 does not extend beyond the front end 95 of the guard90. Accordingly, in the case where the working element is a drill bit155, when the drill bit 155 bores a hole into a work-piece 160 such as apiece of timber the front end 95 of the guard 90 is the only part of thepower drill 10 that will be able to come into contact with thework-piece 160 apart from the drill bit 155 itself. This prevents thejaws 85, 86 at the front end 80 of the driven member 70, which will berotating when the power drill 10 is in the drive mode, from directlycontacting and abrading or otherwise marking the work-piece 160. Anotheradvantage is that when the power tool 10 is in the drive mode the guard90 substantially guards the rotating parts of the driven member 70, suchas the jaws 85, 86, against a user's hair and/or clothing or the likefrom coming into contact and getting caught in the rotating parts of thedriven member 70 such as the jaws or any other part of the driven member70.

The guard 90 may be formed of any suitable material, but is preferablyformed of a substantially rigid material such as plastic, metal or thelike. The guard 90 may be a solid, uniform substantially cylindricalmember or it may have apertures in it or be formed of a number ofelongate members extending from the body 20 of the power drill 10arranged to form a non-complete cylinder type arrangement. Anyarrangement of the guard 90 that meets the criteria set out for theguard 90 of the invention should be considered to fall within the scopeof the invention.

In another form, the guard 90 may include a resilient member such as apiece of rubber in the form of a ring mounted on the round front end 95of the guard 90. The resilient member is mounted to the front end 95 ofthe guard 90 for preventing the jaws 85, 86 comprising the front end 80of the driven member 70, which will be rotating when the power drill 10is in the drive mode, from directly contacting a work-piece 160 for theworking element 155 and from leaving an impression or other unwantedmark on the work piece. The resilient member may be mounted to the guard90 adjacent the front end 80 of the driven member 70, such that at leastin the drive mode the front end 80 of driven member 70 does not extendbeyond the resilient member, the resilient member may be mounted to theguard 90 adjacent and forward of the front end 80 of the driven member70. The resilient member is particularly beneficial where, for example,the work-piece 160 is a piece of relatively soft material such assoft-wood and where the hard metallic jaws 85, 86, which will berotating when the power drill 10 is in the drive mode, pose a risk ofcoming into contact with the soft material and abrading or leaving adivot in the soft material. The resilient member is also particularlybeneficial in preventing the guard 90, which may be relatively hard,from coming into direct contact with the work-piece 160 and causingdamage such as leaving a divot or depression, particularly where thework-piece 160 is relatively soft material such as soft-wood or otherlike soft material

As is shown in FIGS. 1 and 5, the guard 90 includes a gripping surface100 extending from the body 20 of the power drill 10 to the front end 95of the guard 90 adjacent the front end 80 of the of the driven member70. The gripping surface 100 enables a user to grip the power drill 10by not only the handle 60 but also the guard 90. Accordingly, a user cangrip the power drill 10 forward of the rear end 75 of the driven member70 and/or forward of the body 20 of the power drill 10 when the powerdrill 10 is in the drive mode. As such, a user can hold the power drillmuch closer to the working element 155 than has previously been possiblewith existing power tools such as power drills.

As illustrated in FIGS. 1 to 4 and 8 the gripping surface 100 of theguard 90 may include a resilient portion 170 and a non-resilient portion172. The resilient portion 170 of the gripping surface 100 may be formedout of a resilient material such as a soft, spongy polymer, rubber orother like material so as to provide additional grip when a user isgripping the gripping surface 100. Another advantage of the resilientportion 170 of the gripping surface 100 is that it may have shockabsorption properties that insulate the users hand from vibration fromthe power tool. It is to be appreciated, however, that the resilientportion 170 may be substituted by a textured or shaped surface ormaterial which provides additional grip for a user.

In FIGS. 4 and 7 the power drill 10 includes a light source 110 mountedto the guard 90 near the front end 95 of guard 90 and adjacent thedriven member 70. The light source 110 is in a circuit with the battery40 and is operable for providing light in an area of a work-piece 160where the working element 155, such as a drill or screwdriver bit, willcarry out work. In yet another form in which the power drill 10 is amains powered drill and not a battery powered drill, the light source110 may be in circuit with the mains power supply and supplied withpower therefrom. In another form, the light source 110 may be detachablymounted to the front end 95 of the guard 90 or any other part of theguard 90 between the front end 95 and the tool body 20. The detachablelight source 110 may include its own battery or other form of powersupply such that the detachable light source need not be in circuit withthe battery 40 or a mains power supply to the power drill 10.

In FIGS. 3, 4 and 7 the power drill 10 is also provided with a bearing120 mounted between an inner circumferential surface 125 of the guard 90and the head portion 76 of the driven member 70. The bearing 120 may beany type of bearing such as a ball bearing type bearing. Alternatively,the bearing 120 may be a bushing or may simply be replaced by contactingthe inner circumferential surface 125 of the guard 90 directly to thehead portion 76 of the driven member 70. The advantage of thesearrangements is that the driven member 70 is supported forward of therear end 75 of the driven member 70 whereas in existing arrangements,the driven member 70 is only supported behind the rear end 75 of thedriven member 70, some distance away from the working element 155 whichis subject to forces in various directions arising from contact with,and work being conducted, on the work-piece 160.

In FIGS. 1 to 4 the power drill 10 shown includes a mechanicaladjustment means that includes a toggle 130 connected to a locking ring132. The toggle 130 is movable between a drive mode positioncorresponding to the drive mode of power drill 10 and an adjustment modeposition in which the driven member 70 is adjustable for gripping andreleasing a drill or screwdriver bit. In the adjusting position thetoggle 130 is located relatively forward and a protrusion 134 connectedto the toggle 130 engages a forward recess 136 within the guard 90. Thelocking ring 132, which is also connected to the toggle 130, is alsolocated relatively forward and engages and locks an adjustment sleeve140 which in turn locks the adjusting nut 72 to prevent it from rotatingrelative to the head portion 76. Forward or reverse rotation of thedriven member 70 caused by forward or reverse rotation of the motor 30causes co action between the jaws 85, 86, the head portion 76 and theadjusting nut 72 such that the position of the jaws 85, 86 is adjustedinwards or outwards according to the direction of the rotation of thedriven member 70 and of the motor 30. Accordingly, in the preferredembodiment in the driven member 70 is a chuck, forward and reverserotation of the chuck resulting from forward and reverse rotation of themotor 30 causes the jaws 85, 86 to adjust inwards and outwards when thepower tool 10 is in the adjustment mode as determined by the position ofthe toggle 130.

The toggle 130 is also movable to the drive mode position in which thetoggle 130 is located relatively rearward and the protrusion 134connected to the toggle 130 engages a rearward recess 138 within theguard 90. The locking ring 132, which is connected to the toggle 130, isalso located relatively rearward and disengages and unlocks theadjustment sleeve 140 which in turn unlocks the adjusting nut 72relative to the head portion 76 to enable the adjusting nut 72 to rotatewhen the driven member 70 rotates. The advantage of this form of theinvention is that a user can conveniently adjust the driven member 70 togrip and release a drill or screwdriver bit by simply moving the toggle130 forwards or rearwards and activating the motor 30 of the power drill10 in either the forward or reverse direction. This arrangement alsoenables the user to adjust the driven member 70 with the driven member70 substantially enclosed by the guard 90. The power drill 10 alsoincludes a forward/reverse switch 180 that is can be manipulated by auser to cause the motor 30 to rotate in either the forward or reversedirection when the user activates the switch 55. The forward/reverseswitch 180 can achieve this by various suitable ways including by beingable to reverse the flow of current from the battery 40 to the motor 30.

An electronic form of the adjustment means is shown in FIGS. 5 to 7 inwhich instead of utilising a mechanical arrangement between the toggle130 and the adjusting nut 72 for locking and unlocking the adjusting nut72 relative to the head portion 76 the power drill 10 utilises anelectronic actuator 150 to move the locking ring 132 forward andrearward for engaging and disengaging the adjustment sleeve 140 and, inturn, locking and unlocking the adjusting nut 72 such that it remainsstationary relative to the head portion 76 which is rotatable under theaction of the drive means for respectively providing the adjustment modeand drive mode for the power drill 10.

The power drill 10 may also include, as indicated in FIGS. 2 to 4, agearbox 32 between the motor 30 and the drive means 70. The gearbox 32includes more than one setting for the relative speed of rotation of thedriven member 70 relative to the speed of rotation of the motor 30. Thepower tool 10 also includes a sliding switch 33 connected to the gearbox32 for adjusting the gearbox 32 into its various settings.

It will be apparent from the foregoing description that a power tool 10incorporating the invention prevents the driven member 70 of the powertool 10 from directly contacting a work-piece 160 for the workingelement 155 and substantially guards against a user's hair and clothingfrom contacting the front end of the driven member 70 when the powertool 10 is in the drive mode. A power tool 10 incorporating theinvention also provides a reliable and effective means by which rotationof the driven member or chuck can on the one hand drive the workingelement relative to the power tool body and on the other hand cause thedriven member to either grip the working element or release the workingelement or both. The power tool 10 also advantageously provides agripping surface forward of the rear end 75 of the driven member 70.

Finally it is to be understood that various alterations, modificationsand/or additions may be introduced into the constructions andarrangements of the parts previously described without departing fromthe spirit or ambit of the invention.

1. A power tool including: a power tool body; a rotatable driven memberbeing operable for releasably gripping a working element and having afront end and a rear end, the driven member extending from the rear end,located proximally and connected to the power tool body, and terminatingat the front end; the power tool having a drive mode in which rotationof the driven member drives the working element relative to the powertool body and an adjustment mode in which rotation of the driven membercauses the driven member to either grip the working element or releasethe working element or both; a guard connected to the power tool bodyextending over the driven member from the power tool body andterminating adjacent to the front end of the driven member, wherein atleast in the power tool drive mode the driven member rotatesindependently of the guard, the front end of the driven member does notextend beyond the guard and the guard can be gripped by a user when thepower tool is operated in the drive mode.
 2. The power tool of claim 1,wherein the guard has a surface for gripping the power tool between thefront end of the driven member and the power tool body.
 3. The powertool of claim 2, wherein the gripping surface is at least partiallyformed out of a resilient material.
 4. The power tool of claim 3,wherein a majority of the gripping surface is formed out of a resilientmaterial.
 5. The power tool of claim 3, wherein the resilient materialis a soft material.
 6. The power tool of claim 1, wherein the guardterminates adjacent and forward of the front end of the driven member inthe power tool drive mode.
 7. The power tool of claim 1, furtherincluding a resilient member mounted to the guard adjacent the front endof the driven member, wherein at least in the power tool drive mode thefront end of the driven member does not extend beyond the resilientmember for preventing the guard from leaving an impression on a workpiece.
 8. The power tool of claim 7, wherein the resilient member ismounted to the guard adjacent and forward of the front end of the drivenmember.
 9. The power tool of claim 1, wherein the driven member drivesmovement of the working element by substantially moving relative to anaxis of the driven member and the guard is substantially axially alignedwith the axis of the driven member.
 10. The power tool of claim 1,wherein the guard is rotatable relative to the body of the power toolfor adjusting the amount of torque supplied to the driven member. 11.The power tool of claim 10, wherein the amount of torque supplied to thedriven member is adjusted by a torque controller that is actuable todifferent torque settings by the rotation of the guard.
 12. The powertool of claim 11, wherein the torque controller is a mechanical torquecontroller.
 13. The power tool of claim 10, wherein the guard includes agraduated indicator for different amounts of torque.
 14. The power toolof claim 10, wherein the body includes a graduated indicator fordifferent amounts of torque.
 15. The power tool of claim 1, wherein theguard is substantially cylindrical and tapers from a larger diameter atthe power tool body and to a smaller diameter opening adjacent the frontend of the driven member.
 16. The power tool of claim 1, wherein theguard is integral with the power tool body.
 17. The power tool of claim1, wherein the guard is detachable from the power tool body to revealthe driven member.
 18. The power tool of claim 1, further including alight source mounted to the guard adjacent the front end of the drivenmember for providing light on a work area for the working element. 19.The power tool of claim 18, wherein the light source is detachable fromthe guard.